Increased demand for cleaner fuel due to environmental concern and depleting petroleum reserves in the world coupled with deteriorating quality of the crude oil have led a surge of research for renewable and clean fuel sources. One of the renewable sources may be the oil originating from vegetables and animals such as waste restaurant oil, soybean oil, Jatropha oil, and algae oil etc. This also helps in rural development by providing better cost for their products. But these oils originating from vegetables and animals cannot be used directly in the engine due to the problems inherent with these oils such as higher viscosity and oxygen content and poor atomization and lubricity. Therefore before using in the engine these oils are to be converted into bio-diesel or green diesel. Bio-diesel which is Fatty Acid Methyl Esters (FAME) is produced by transesterification of fatty acids in triglycerides. To use bio-diesel in the engine requires some modification and additional disadvantages are poor performance in cold weather and poor emission. Another way of effectively using these renewable oils is by converting these oils into hydrocarbons with much higher cetane value than conventional diesel fuel. This process involves conversion of fatty acids in triglycerides into linear and/or iso-alkanes. This may be obtained by hydrodeoxygenation, decarbonylation, decarboxylation, isomerisation and hydrocracking or a combination of two or more thereof.
The patented literature presents some documents in the hydrogenation of vegetable oil, but these documents do not consider in their scope the intended range covered by this invention.
U.S. Pat. No. 2,163,563 discloses the hydrogenation of vegetable oils combined with mineral oil over a reduced Ni catalyst supported in alumina in the presence of hydrogen at high pressure [5 MPa to 50.6 MPa (56 to 500 atmospheres)]. However, this patent does not involve hydrotreatment of a combined load of petroleum and vegetable oils through an HDT process. U.S. Pat. No. 4,300,009 describes a process for generating the product having the boiling point at the range of gasoline boiling point range. This process involves catalytic conversion of anabolites (substances formed in the anabolic process) as resins, vegetable oils and fats in liquid hydrocarbons over zeolites with an effective pore size bigger than 5 Angstrom. U.S. Pat. No. 5,705,722 describes a process to produce additives for diesel fuel which have higher cetane number and may improve ignition of the fuel. The process involves hydroprocessing of the biomass, containing a high proportion of unsaturated fatty acids, wood oils, animal fats and other mixtures in the presence of hydrogen over catalyst. This mixture is then separated and fractioned to obtain a hydrocarbon product with boiling point at the range of diesel's boiling point, being this product the additive with a high cetane number. However the addition of a petroleum hydrocarbon to the biomass load which is being hydroprocessed is not mentioned within this document.
U.S. Pat. No. 4,992,605 describes a process to obtain a stream with a high cetane number to be added to the diesel in the refinery. The process involves hydroprocessing of vegetable oils such as canola or sunflower oil, palm and wood oil that is a waste product from the wood pulp industry, to produce hydrocarbon products in the diesel boiling range by using sulfided catalyst (NiMo and CoMo) in the presence of hydrogen (pressure of 4 to 15 MPa) and temperature in the range of 350° C. to 450° C. This patent does not consider a mixture of a hydrocarbon with vegetable oil in the hydrorefining. Patents U.S. Pat. Nos. 7,491,858, 7,459,597B2, describe production of diesel fuel from vegetable and animal oils and also the further isomerization of obtained hydrocarbons using catalysts known in the prior art. Patent WO 2008054442 describes a process for converting triglycerides to hydrocarbons. U.S. Pat. No. 4,300,009 describe the production of hydrocarbons such as gasoline and chemicals such as para-xylene from plant oils such as corn oil by using of crystalline aluminosilicate zeolites. US 2004/0230085 A1 discloses a process for treating a hydrocarbon component of biological origin by hydrodeoxygenation followed by isomerization.
WO 2009/039000, WO 2009/039335, WO/2009/039347 describe a process which comprises one or more steps to hydrogenate, decarboxylate, decarbonylate, (and/or hydrodeoxygenate) and isomerize the renewable feedstock, the consumption of hydrogen in the deoxygenation reaction zone is reduced by using at least one sulfur containing component which also operates to maintain the catalyst in a sulfided state.
Patents 0175NF2012; 0176NF2012, describe a single step catalyst and process for hydroconversion of vegetable oils triglycerides and free fatty acids to directly to iso-paraffins, paraffins, cyclic and aromatics in the kerosene range to produce aviation fuel.
The conversion of renewable feed stocks into aviation fuel and other hydrocarbons is energy intensive. These are highly exothermic reactions with very high hydrogen consumption, which is major concern for commercial realization of these processes. These highly exothermic reactions, not only decreases the catalyst life but also leads to unwanted cracking and coke formation reactions in catalyst pores; further leading to high pressure drop, low catalyst life and costly process. The hydrogen requirement is increased as the unsaturated hydrocarbons formed due to unwanted cracking reactions gets saturated and hence require extra hydrogen which further adds up the cost. The process and catalyst discussed in earlier literatures does not describe the utility of cold feed stream and its advantages in processing these renewable feedstocks. Also the process discussed does not describe an efficient heat utilization methodology to be followed for these highly exothermic reactions.
To realize a commercial future of these feedstocks, it is very necessary to develop technologies which would deliver hydrocarbon fuels including aviation fuel at competitive prices to crude based fuels. A single step process where hydrogen requirement for conversion of these renewable feed stocks would be less along with reactions with controlled exothermicity is highly desirable. A process and catalyst where these renewable feedstocks are converted selectively to paraffins, isoparaffins, cyclics and aromatics in C1-C24 range hydrocarbons directly without additional gas requirement for quenching, with reduced hydrogen consumption and controlled exothermicity is required.